Hydraulic timing mechanism



Jan. 1, 1946. RE. PRICE 2,392,251

HYDRAULIC TIMING MECHANISM I v Original Filed Feb. 28, 1940 2 Sheets-Sheet 47 f I I Zinveixtor RALPH E. PRICE a (Ittomeg was; Jan. 1, i945 NT OFFICE maa'uuc rnumo mechanism Ralph E. Prlcalllghiield, Md, assignor to Landis Tool Company,

Original 321,310, vembcr Waynesboro, Pa.

application February 28, 1940, Serial No.

new Patent No. 2,335,356, dated 30, 1943. Divided No- :1 this applicaon April 25, 1941, Serial No. 390,433

- 1Cllim.

division of Price et al. application Serial No. 321,310, filed February 28, l940,-now Patent No. 2,335,356, granted November 30, 1943, and relates to timing mechanisms. particularly of the hydraulically operated type.

This invention is a It is an object of this invention to provide a timing mechanism which will be simple in construction and operation and inexpensive.

A further object is to provide a timing mechanism which is c pable of an infinite number of variations.

A further object is to reset the timing mechanism after it has completed its function.

Figure 11s an end elevation of a machine partly I in section.

Figure 2 is a sectional plan view of my invention.

Figure 3 is a piping diagram showing an application of my timer.

In order to control hydraulically actuated movements by a timing mechanism it is essential that the mechanism function at a uniform rate under all conditions of temperature, otherwise in a given time it will move at one rate and thru a given distance if the hydraulic medium is cold and at a diiferent rate and thru a different distance if the medium is warm. If the timing device is to be operated hydraulically it is obviously important that it must function at a uniform rate at all times.

In order to assure such operation, of a relief valve which is described in my copending application Serial No. 390,432, filed April 25, 1941, for Relief valve. Briefly it use is made consists of a differential piston I in acylinder I34. One end of said piston is subjected to a pressure determined by throttle valve I38, and the other end to a pressure determined by the resistance offered by the driven part or parts. The large portion of said piston controls an exhaust passage Z thru which excess fluid may escape. The eflect of this device on a hydraulic system is that the driven parts all function at a uniform rate regardless of the temperature of the fluid. The valve I 30 maintains constant flow regardless of viscosity because it is actuated by fluid under pressure instead of by a spring. The pressure of the fluid varies with viscosity and therefore the setting of the relief valve also changes and instead of a change in flow the flow remains constant. For further details concerning the operation-of this device, reference is made to the above Serial No. 390,432.

In Figure 1. my invention is shown as applied mentioned co-pending application and claimed to the wheel feed mechanism of the parent application. Numeral I0 indicates-the bed of a grinding machine, I I a. work carriage slidably mounted thereon, I2 a swivel table mounted for angular adjustment on said carriage, I3 a headstock, and I l a footstock. both mounted on said table. Any suitable driving device on the headstock serves to rotate the work piece: Carriage II may be shifted manually by means of handwheel I8 thru suitable mechanism, not shown. When actuated by power the direction of movement of the car-,-

'riage is controlled by a reversing lever I9 actuated by dogs 20 and 2| on dog rack 22. A wheel base 25 having a grinding wheel 26 rotatably mounted thereon is slidably mounted on the bed I0 for movement toward and from the work carriage. A cover member 21 hinged for easy inspection encloses the wheel base and grinding wheel and has a separate compartment therein for each of said parts. A handwheel 20 provides a manual means for shifting said wheel base toward and from the work.- The means for shifting said wheel base by power consists briefly of a piston 46 in a cylinder 41. Fluid under pressure is directedto one side or the other of said 1 cylinder thru lines 84 or 86 by a valve which may be shifted in one direction by fluid under pressure applied thru line H3, and in the opposite direction by a spring I0. 7

The fluid under pressure for shifting said valve 00 is supplied thru line II3 by a timing valve shown in Figures 2 and 3. Said valve consists in the valve member I00 slidably mounted in a bore MI in cylindrical housing I02, sometimes referred to hereafter as a timer. One end I03 of said valve is smaller in diameter than the rest of the valve and fits in a bore I 00 of corresponding diameter formed in a member I05 inserted in bore I0 I. The portion of said valve which may be acted on by fluid under pressure in lines H4 and H5 is therefore smaller than the opposite end thereof. An end plate I06 has a line I01 therein leading to bore I05. Another end plate I 00 has a line I09 therein leading'to bore "II. On one side of housing I02 are two lines H0 and III located toward the right hand end of the valve. In the position of valve I00 shown, line III is connected thru peripheral groove I I2 of valve I00 with a line us on the opposite side of said houslng. On said opposite side but toward the left end-of the valve are two additional lines Ill and I I5. Said lines are connected by a passage H6 in which is located a ball check valve which permits passage of fluid from lines I II to I I5. Valve I00 has a closed bore forming a passage I I! which is connected to the chamber at the left end of bore IOI thru a port 0. Spaced axially from 4 saidport is a second port IIO joining said bore IN and passage I I1 thru a peripheral groove I20.

Said groove forms a chamber between said valve and said bore IOI. Movement of valve I to the left is retarded by the fluid exhausting from the bore I 0| thru line H0 and thru a throttle valve I2I in said line.' When the valve I00. moves to a point where port H9 coincides with line III, the

vfluid" may be released-thru passage III, passage IIG, port H0 in said valve, and exhaust line Ill 0 in the housing, thus permitting said valve to move quickly to reverse position.

Operation Fluid under pressure directed by valve 300 thru lines 420 and "I passes first thru a hydraulic timer I02. Part of said fluid passes from line 42! thru line I09 to shift the valve member I00 from right to left. Another part of said fluid passes.

from said line 2| thru line III and peripheral groove 2 of valve I00 thru line 3 to shift feed valve 80 to operative position and hold it there for a predetermined time. Movement of valve I00 from right to left iscontrolled by the fluid being forced out thru line II! and thru throttle valve I2I into line' I against pump pressure since the exposed area of the left end of said valve is less than that of the right end. When valve I00 opens line I I4 thru peripheral groove I20, passage Ill, and ports H8 and II! to bore IOI, further movement is uncontrolled and said-valve moves exhaust outlet. Said lever may be shifted maning position.

' ually or automatically by power controlled by said I timing valve. Fluid vunder pressure in line I I4 will shift valve I00 to the right when line I is connected to an exhaust outlet as described above. If it is desired to stop the grinding operation before the end of the cycle, the operator can by shifting lever 024 open line "I to exhaust so that fluid under pressure in line II! will shift valve I00 to the-right. Line III which is connected to line 42f will also be opened to exhaust. Line III being connected thru line II3 to reversing valve 00 will permit the exhaust of fluid therefrom. Spring I6 may then reset said reversing valve to direct fluid under pressure to withdraw the wheel DD r I claim:

'A hydraulic system a pump, a motor for shifting a tool carriage toward and from operative position, a reversing valve for said motor, said valve being normally held in position for shifting said motor in one directlon, a pressure operated valve for directing fluid under pressure to actuate said reversing valve away from normal position and thus to cause said tool carriage to move to operative position, a by-pass relief valve adapted to compensate for variation in viscosity in the hydraulic medium whereby to insure uniform operation of all mechanisms in the system regardless of the viscosity of the fluid, said pressure operated valve being constructed to deliverifluid under pressure to said reversing valve for a,perlod dependent on the rate of movement of said pressure operated valve and thereafter, to cut oil! the flow of fluid under pressure thereto and to connect said reversing valve with an exhaustline whereby said reversing valve may ti'on and the tool carriage withdrawn from work- RA'LPH E. PRICE. 7

for machine tools including be returned to normal pOsi- 

